Method for removing micro-bubbles and/or particles from liquid, liquid supply apparatus and immersion exposure apparatus

ABSTRACT

A liquid supply apparatus capable of removing micro-bubbles and particles is described, including a pipe, a laser provider and at least one micro-bubble/particle outlet. The laser provider provides a laser crossing the pipe, wherein the laser is provided in a manner such that a micro-bubble/particle blocking/repelling barrier is formed crossing the pipe blocking or repelling micro-bubbles, particles or both in the liquid in the pipe. The micro-bubble/particle outlet is disposed on the pipe between the barrier and the liquid inlet of the pipe, adjacent to the barrier for discharging micro-bubbles, particles or both.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates to a method for removing micro-bubble and/orparticles from a liquid and a liquid supply apparatus utilizing themethod, and more particularly to a method of utilizing laser to removemicro-bubble and/or particles from a liquid, a liquid supply apparatusutilizing the method, and an immersion exposure apparatus thatincorporates the liquid supply apparatus.

2. Description of Related Art

Liquid is used in many industries as a medium for reaction ormeasurement, etc. However, micro-bubbles and/or particles in a liquidfrequently cause problems.

Taking the semiconductor industry as an example, a liquid like water isused in the immersion lithography that is recently developed for thefollowing reasons. As the linewidth of semiconductor process is to bereduced, the most direct way is to reduce the wavelength of the exposurelight and thereby enhance the resolution. However, there are so manyissues to be solved, such as the laser source, photomask material, lensmaterial and photoresist material, for the new-generation lithographyprocess of 157 nm. For example, it is difficult to fabricate lenses ofcalcium fluoride suitable for 157 nm exposure, for the lenses eitherhave many defects or cause significant aberrations and thus cannotproject a clear image on the wafer. Hence, the immersion lithography isdeveloped, which allows the resolution to be enhanced based on current193 nm lithography instead of the development of 157 nm lithography. Theimmersion lithography method is to inject water between the light sourceand the wafer in a 193 nm exposure system to reduce the wavelength to132 nm, so that 65 nm, 45 nm and even 32 nm processes can be supportedby the immersion lithography instead of current dry lithography systems.

However, there are still some technical problems in immersionlithography. For example, the exposure light may be scattered by themicro-bubbles or particles in the water in the immersion exposure systemso that many defects are incurred in the image transferred to the wafer.

SUMMARY OF THE INVENTION

Accordingly, this invention provides a method for removing micro-bubblesand/or particles from a liquid, which can easily remove micro-bubblesand/or particles.

This invention also provides a liquid supply apparatus that utilizes theabove method of this invention to remove micro-bubbles and/or particlesfrom a liquid.

This invention also provides a immersion exposure apparatus thatincorporates the liquid supply apparatus of this invention.

It is particularly noted that in the specification and claims of thisinvention, the term “micro-bubble(s)/particle(s)” means micro-bubble(s),particle(s) or both of them, and the term “blocking/repelling” meansblocking, repelling or both of them.

The liquid supply apparatus of this invention includes a pipe with aliquid inlet and a liquid outlet, a laser provider for providing lasercrossing the pipe, and at least one micro-bubble/particle outlet. Thelaser is provided in a manner such that a micro-bubble/particleblocking/repelling barrier is formed capable of blocking/repellingmicro-bubbles/particles in the liquid in the pipe. Themicro-bubble/particle outlet is disposed on the pipe between the barrierand the liquid inlet, adjacent to the micro-bubble/particleblocking/repelling barrier for discharging micro-bubbles/particles.

The method for removing micro-bubbles and/or particles from a liquid ofthis invention is described as follows. A pipe having amicro-bubble/particle outlet thereon is provided. The liquid is thenconducted through the pipe while a laser is provided crossing the pipein a manner such that a micro-bubble/particle blocking/repelling barrieris formed in the pipe for blocking/repelling micro-bubbles/particles inthe liquid. The micro-bubble/particle outlet is located on the pipebetween the barrier and the liquid inlet, adjacent to the barrier fordischarging micro-bubbles/particles.

The immersion exposure apparatus of this invention includes awafer-scanning stage, an exposure optical system, an immersion chamberand a liquid supply apparatus of this invention. The wafer-scanningstage is for supporting a wafer with photoresist thereon or a cleaningwafer. The exposure optical system is disposed above the wafer-scanningstage. The immersion chamber is disposed between the wafer-scanningstage and the exposure optical system, for accommodating an exposuremedium in exposure or a solvent in a cleaning operation. The liquidsupply apparatus is for supplying the exposure medium or the solvent,including a reservoir for storing the exposure medium or the solvent, asupply pipe, a laser provider and at least a micro-bubble/particleoutlet. The supply pipe includes a liquid inlet connected with thereservoir and a liquid outlet connected with the immersion chamber. Thedescriptions of the laser provider and the at least onemicro-bubble/particle outlet are the same as the above mentioned.

In some embodiments of this invention, a cross section of the pipe has acircular shape or a rectangular shape.

In some embodiments, the micro-bubble/particle blocking/repellingbarrier is a substantially planar barrier. The planar barrier may besubstantially parallel with a cross-sectional plane of the pipe or beinclined in the flow direction of the liquid in the pipe. Alternatively,the planar barrier is substantially perpendicular to the sidewalls ofthe pipe or is inclined to the sidewalls. When the planar barrier formsa sharp angle with a sidewall of the pipe as viewed from the upstream ofthe barrier, the micro-bubble/article outlet is preferably disposed onthe sidewall or the top wall of the pipe adjacent to the sharp angle,wherein the “upstream” of the barrier is defined by the flow directionof the liquid in the pipe.

In some embodiments, the micro-bubble/particle blocking/repellingbarrier is a sectional barrier, which may include two or more planarparts. When at least one planar part of the sectional barrier forms asharp angle with a sidewall of the pipe as viewed from the upstream ofthe barrier, the micro-bubble/particle outlet is preferably disposed onthe sidewall or the top wall of the pipe adjacent to the sharp angle.When at least one planar part of the sectional barrier forms an obtuseangle with a sidewall of the pipe as viewed from the upstream of thebarrier, the micro-bubble/particle outlet is preferably disposed on thetop wall of the pipe adjacent to the intersection of two adjacent planarparts.

In certain embodiments, the micro-bubble/particle outlet is disposed onthe top wall or a sidewall of the pipe. The blocking/repelling barriermay extend through at least a part of the micro-bubble/particle outlet.The light intensity in the blocking/repelling barrier may have asubstantially gradient distribution. The liquid outlet may be connectedwith a liquid inlet of an immersion exposure system.

Because this invention utilizes laser to form a micro-bubble/particleblocking/repelling barrier in the flow path of the liquid, themicro-bubbles and/or particles in the liquid can be removed easily.

In order to make the aforementioned and other objects, features andadvantages of the present invention comprehensible, a preferredembodiment accompanied with figures is described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B schematically illustrate two embodiments of the liquidsupply apparatus of this invention, wherein the micro-bubble/particleblocking/repelling barrier is substantially planar and substantiallyparallel with a cross-sectional plane of the pipe.

FIGS. 2A and 2B schematically illustrate two more embodiments of theliquid supply apparatus of this invention, wherein themicro-bubble/particle blocking/repelling barrier is inclined to the flowdirection of the liquid in the pipe.

FIGS. 3A and 3B schematically illustrate two more embodiments of theliquid supply apparatus of this invention, wherein themicro-bubble/particle blocking/repelling barrier is substantially planarand substantially perpendicular to the top wall of the pipe.

FIGS. 4A-4C schematically illustrate three more embodiments of theliquid supply apparatus of this invention, wherein themicro-bubble/particle blocking/repelling barrier is a sectional barrierincluding two or more substantially planar parts.

FIG. 5 schematically illustrates an immersion exposure apparatusaccording to an embodiment of this invention into which a liquid supplyapparatus of this invention is incorporated for supplying a liquid to beused in the immersion exposure apparatus.

DESCRIPTION OF EMBODIMENTS

Some embodiments are provided below to further explain this invention,which are not intended to limit the scope of this invention. It is alsonoted that a method of forming a barrier (force field) capable ofblocking/repelling micrometer bubble/particle with laser can be derivedbased on the descriptions of U.S. Pat. No. 6,815,664, which is intendedto sort micrometer particles in a liquid.

Referring to FIG. 1A, in this embodiment, a liquid supply apparatus 10capable of removing micro-bubbles and particles includes a pipe 12 and alaser provider 14. A cross section of the pipe 12 may have a circularshape or a rectangular shape, and the material of the same may beplastic like PVC, quartz or glass, etc. The laser provider 14 provideslaser crossing the pipe 12, wherein the laser is provided in a mannersuch that a micro-bubble/particle blocking/repelling barrier 16 isformed. When water, an organic solvent or a mixed liquid from the liquidinlet 12 a of the pipe 12 flows through the barrier 16,micro-bubbles/particles 11 are blocked and/or repelled by the barrier 16to accumulate before the barrier 16, so that the liquid passing thebarrier 16 contains few or even no micro-bubbles or particles. Theliquid supply apparatus 10 further includes at least onemicro-bubble/particle outlet 18 disposed on the pipe 12 between thebarrier 16 and the liquid inlet 12 a adjacent to the barrier 16. Withthe aid of the liquid flow, the micro-bubbles/particles 11 accumulatedbefore the barrier 16 are discharged from the micro-bubble/particleoutlet 18.

The shape and location of the micro-bubble/particle blocking/repellingbarrier 16 as well as the location and number of themicro-bubble/particle outlet 18 can be varied as required. Somevariations are described as follows, which are not intended to limit thescope of this invention.

Referring to FIGS. 1A and 1B, in these embodiments, themicro-bubble/particle blocking/repelling barrier 16 formed with thelaser provider 14 is substantially parallel with a cross-sectional plane19 of the pipe 12. The barrier 16 may be formed at the downstream sideof the micro-bubble/particle outlet 18 adjacent to the same, as shown inFIG. 1A. Alternatively, the barrier 16 may extend through a part of themicro-bubble/particle outlet 28, as shown in FIG. 1B.

Referring to FIGS. 2A and 2B, in these two embodiments, the laserprovider 14 provide a laser in a manner such that the blocking/repellingbarrier 26 formed is inclined in the flow direction of the liquid fromthe inlet 12 a to the outlet 12 b of the pipe 12 and forms a sharp angleθ with a cross-sectional plane 19 of the pipe 12. Similarly, the barrier26 may be formed with its top part at the downstream side of themicro-bubble/particle outlet 18, as shown in FIG. 2A, or formed througha part of the micro-bubble/particle outlet 28, as shown in FIG. 2B. Infact, the location of the micro-bubble/particle outlet 18 or 28 is notparticularly limited, if only the micro-bubbles/particles can bedischarged easily.

In an embodiment, the micro-bubble/particle blocking/repelling barrierformed with the laser provider 14 may be a substantially planar one, asshown in FIGS. 3A-3B. In another embodiment, the barrier is formed as asectional one, which may include two or more substantially planar partsas shown in FIGS. 4A-4C. The pipe 12 in each of FIGS. 3A-3B and 4A-4Chas a rectangular cross section for simplifying the followingdescriptions, but the shape of the pipe applicable to this invention isnot limited to that.

Referring to FIGS. 3A-3B, the micro-bubble/particle blocking/repellingbarriers 36 a and 36 b formed by the laser provider 14 are substantiallyplanar ones. In FIG. 3A, the barrier 36 a is substantially perpendicularto the extending direction x of the pipe 12, which is the flow directionof the liquid in the pipe 12 in this case. In FIG. 3B, the barrier 36 bis inclined to the sidewalls of the pipe 12 and forms a sharp angle αwith the extending direction x of the pipe 12. The intersection of thebarrier 36 a or 36 b and a sidewall of the pipe 12 is substantiallyparallel with that of a cross-sectional plane 19 and the sidewall inthese two embodiments, but the two intersections may alternatively notbe parallel with each other in other embodiments.

Referring to FIG. 3A, when the barrier 36 a is a planar one that issubstantially perpendicular to the extending direction x of the pipe 12,a micro-bubble/particle outlet 38 a can be disposed at any locationabove the pipe 12 adjacent to the barrier 36 a. An extramicro-bubble/particle outlet 38 b may be disposed on a sidewall of thepipe 12 adjacent to the barrier 36 a.

Referring to FIG. 3B, when the barrier 36 b is a planar barrier thatforms a non-right angle α with the extending direction x of the pipe 12and thus forms a sharp angle and a obtuse angle with respectivesidewalls of the pipe 12 as viewed from the upstream of the barrier 36 bdefined by the flow direction of the liquid from 12 a to 12 b, it ispreferred to dispose a micro-bubble/particle outlet 38 c above the pipe12 adjacent to the sharp angle and/or a micro-bubble/particle outlet 38d on a sidewall of the pipe 12 adjacent to the sharp angle.

Referring to FIGS. 4A-4C, the micro-bubble/particle blocking/repellingbarriers formed with the laser provider are sectional ones, which may,but are not limited to, include two or more substantially planar parts.The sectional barrier 46 a in FIG. 4A has two planar parts 58 a and 56 athat form two sharp angles β and γ respectively with the sidewalls 12 cand 12 d of the pipe 12 as viewed from the upstream of the barrier 46 a.The sectional barrier 46 b in FIG. 4B has two planar parts 58 b and 56 bthat form two obtuse angles β and γ respectively with the sidewalls 12 cand 12 d of the pipe 12 as viewed from the upstream of the barrier 46 b.The sectional barrier 46 c in FIG. 4C has three planar parts 56 c, 58 cand 60 c, wherein the planar part 56 c forms a sharp angle β with thesidewall 12 c and the planar part 60 c forms an obtuse angle γ with thesidewall 12 d as viewed from the upstream of the barrier 46 c.

Referring to FIG. 4A, when the sectional barrier 46 a has two planarparts 58 a and 56 a that form two sharp angles β and γ respectively withthe sidewalls 12 c and 12 d of the pipe 12 as viewed from the upstreamof the barrier 46 a, it is preferred to dispose one or moremicro-bubble/particle outlets at one or more locations among thelocations on the two sidewalls 12 c and 12 d and on the top wall of thepipe 12 that are adjacent to the sharp angles β and γ. The liquid supplyapparatus in FIG. 4A merely has a micro-bubble/particle outlet 48 adisposed above the pipe 12 adjacent to the sharp angle γ and amicro-bubble/particle outlet 48 b disposed on the sidewall 12 c adjacentto the sharp angle β.

Referring to FIG. 4B, when the sectional barrier 46 b has two planarparts 58 b and 56 b that form two obtuse angles β and γ respectivelywith the sidewalls 12 c and 12 d as viewed from the upstream of thebarrier 46 b, a micro-bubble/particle outlet 48 c is preferably disposedabove the pipe 12 adjacent to the intersection of the two planar parts56 b and 58 b that form an angle δ between them.

Referring to FIG. 4C, when the sectional barrier 46 c has three planarparts 56 c, 58 c and 60 c wherein the planar parts 56 c and 60 crespectively form a sharp angle β and an obtuse angle γ with thesidewall 12 c and 12 d as viewed from the upstream of the barrier 46 c,three micro-bubble/particle outlets 48 d, 48 e and 48 f may be disposedrespectively above the pipe 12 adjacent to the sharp angle β, on thesidewall 12 c adjacent to the sharp angle β, and above the pipe 12adjacent to the intersection of the two planar parts 58 c and 60 c thatform an angle δ smaller than 180° as viewed from the upstream of thebarrier 46 c. It is also feasible to disposed one or twomicro-bubble/particle outlets at one or two of the above threelocations. In principle, a micro-bubble/particle outlet is disposed at alocation where micro-bubbles/particles easily accumulate, i.e., a partof the sidewall of the pipe at the downstream side of the barrier anddirectly adjacent to the barrier.

The sectional micro-bubble/particle blocking/repelling barriers 46 a-46c in the embodiments illustrated in FIGS. 4A-4C each has an overallextending direction that is substantially parallel with thecross-sectional plane 19. Nevertheless, the overall extending directionof a sectional micro-bubble/particle blocking/repelling barrier in thisinvention is not limited to be parallel with a cross-sectional plane ofthe pipe and may be unparallel with the latter.

Besides, the light intensity in an aforementioned micro-bubble/particleblocking/repelling barrier of this invention may have a substantiallyuniform distribution or have a substantially gradient distribution. Themicro-bubble/particle blocking/repelling barrier may alternatively beformed in a multi-points or multi-lines arrangement caused by lightspots and light planes to enhance the removal efficiency of themicro-bubbles/particles.

Referring to FIG. 5, the method for removing micro-bubbles/particles andthe liquid supply apparatus of this invention can be applied toimmersion lithography for providing a liquid with few or even nomicro-bubbles and/or particles. An example of an exposure apparatus ofan immersion lithograph system that utilizes the liquid supply methodand apparatus of this invention is illustrated in FIG. 5.

Referring to FIG. 5, the exposure apparatus 500 of an immersionlithograph system includes a wafer-scanning stage 528 for supporting awafer having a photoresist layer thereon or a cleaning wafer 510. Theoptical housing 512 includes an optical system 513 for accommodating amask (not shown). The optical system 513 includes a light source 515,such as a laser, and an objective lens 516 configured correspondinglyabove the wafer-scanning stage 528. The immersion chamber 518,configured below the objective lens 516 but above the scanning stage528, is used for accommodating a liquid 532, for example, an exposuremedium like water, or a solvent for cleaning the objective lens 516,such as water.

The immersion chamber 518 can be an air-tight chamber formed bysupplying an inert gas through a gas inlet duct (not shown). The liquidin the immersion chamber 518 is supplied by a liquid supply apparatus 50of this invention. The liquid supply apparatus 50 includes a supply pipe52 having a liquid inlet 52 a and a liquid outlet 52 b and a laserprovider 54 for forming a micro-bubble/particle blocking/repellingbarrier (not shown), as mentioned above, and further includes areservoir 56. The reservoir 56 is for storing the liquid 532, the liquidinlet 52 a of the supply pipe 52 is connected with the reservoir 56, andthe liquid outlet 52 b is connected with the immersion chamber 518.After being used, the liquid 532 in the immersion chamber 518 can bedischarged via a discharge pipe 524.

In the lithograph process, a light beam 515 a, such as a laser beam, istransmitted through the objective lens 516 and the liquid medium in theimmersion chamber 518 onto the photoresist, and the image of the mask istransferred to the photoresist on the wafer.

Subsequent to the exposure process, a cleaning operation may beperformed by supplying a solvent from the liquid supply apparatus 50 tothe immersion chamber 518 to remove the contaminants on the objectivelens 516. To improve the cleaning effect, the exposure apparatus 500 mayfurther includes an ultrasonic vibrator for vibrating the cleaningsolvent, such as an ultrasonic vibrator 530 set around the immersionchamber 518.

Nevertheless, the above method and apparatus of this invention are notlimited to apply to the immersion lithography, but can also be appliedto any other industry that needs removal of micro-bubbles and/orparticles.

The present invention has been disclosed above in the preferredembodiments, but is not limited to those. It is known to persons skilledin the art that some modifications and innovations may be made withoutdeparting from the spirit and scope of the present invention. Therefore,the scope of the present invention should be defined by the followingclaims.

1. An immersion exposure apparatus, including an immersion chamber foraccommodating an exposure medium in exposure or a solvent in a cleaningoperation; and a liquid supply apparatus for supplying a liquid as theexposure medium or the solvent, comprising: a reservoir for storing theexposure medium; a supply pipe including a liquid inlet and a liquidoutlet, wherein the liquid inlet is connected with the reservoir and theliquid outlet is connected with the immersion chamber; a laser providerfor providing a laser crossing the supply pipe, the laser is provided ina manner such that a micro-bubble/particle blocking/repelling barrier isformed capable of blocking or repelling micro-bubbles, particles or bothfrom the liquid in the exposure medium; and at least onemicro-bubble/particle outlet on the supply pipe between themicro-bubble/particle blocking/repelling barrier and the liquid inlet,adjacent to the micro-bubble/particle blocking/repelling barrier fordischarging micro-bubbles, particles or both.
 2. The immersion exposureapparatus of claim 1, wherein a cross section of the supply pipe has acircular shape or a rectangular shape.
 3. The immersion exposureapparatus of claim 1, wherein the micro-bubble/particleblocking/repelling barrier is a planar barrier.
 4. The immersionexposure apparatus of claim 3, wherein the planar barrier issubstantially parallel with a cross-sectional plane of the supply pipeor is inclined to a flow direction of the liquid in the supply pipe. 5.The immersion exposure apparatus of claim 3, wherein the planar barrieris substantially perpendicular to sidewalls of the supply pipe or isinclined to the sidewalls of the supply pipe.
 6. The immersion exposureapparatus of claim 5, wherein the planar barrier forms a sharp anglewith a sidewall of the supply pipe as viewed from upstream of the planarbarrier, and the micro-bubble/article outlet is disposed on the sidewallor a top wall of the supply pipe adjacent to the sharp angle, whereinthe upstream of the planar barrier is defined by a flow direction of theliquid in the supply pipe.
 7. The immersion exposure apparatus of claim1, wherein the micro-bubble/particle blocking/repelling barrier is asectional barrier including a plurality of planar parts.
 8. Theimmersion exposure apparatus of claim 7, wherein when at least oneplanar part of the sectional barrier forms a sharp angle with a sidewallof the supply pipe as viewed from upstream of the sectional barrier, themicro-bubble/particle outlet is disposed on the sidewall or a top wallof the supply pipe adjacent to the sharp angle, wherein the upstream ofthe sectional barrier is defined by a flow direction of the liquid inthe supply pipe; and when at least one planar part of the sectionalbarrier forms an obtuse angle with a sidewall of the supply pipe asviewed from the upstream of the sectional barrier, themicro-bubble/particle outlet is disposed on a top wall of the supplypipe adjacent to an intersection of two adjacent planar parts.
 9. Theimmersion exposure apparatus of claim 1, wherein themicro-bubble/particle outlet is disposed on a top wall or a sidewall ofthe supply pipe.
 10. The immersion exposure apparatus of claim 1,wherein the micro-bubble/particle blocking/repelling barrier extendsthrough at least a part of the micro-bubble/particle outlet.
 11. Theimmersion exposure apparatus of claim 1, wherein light intensity in themicro-bubble/particle blocking/repelling barrier has a substantiallygradient distribution.
 12. The immersion exposure apparatus of claim 1,further comprising a discharge pipe connected with the immersion chamberfor discharging the exposure medium.
 13. The immersion exposureapparatus of claim 1, further comprising: a wafer-scanning stage, forsupporting a wafer having a photoresist layer thereon or a cleaningwafer; and an exposure optical system disposed above the wafer-scanningstage.